1. Field of the Invention
The present invention generally relates to a pressure developing apparatus and particularly relates to a pressure developing apparatus in which a microcapsule sheet having photo-sensitive microcapsule applied thereon and carrying a latent image formed thereon and a developer sheet having a developer applied thereon are put on each other and pressed by a pressure means so as to form a picture on the developer sheet.
As the microcapsule sheet and the developer sheet, those disclosed in U.S. Pat. No. 4,399,209 may be used.
2. Description of the Prior Art
In the pressure developing apparatus in which a microcapsule sheet having photo-sensitive microcapsule applied thereon and carrying a latent image formed thereon and a developer sheet having a developer applied thereon are put on each other and pressed by a pressure means so as to form a picture on the developer sheet, it is very important to keep even the respective surfaces of a pair of pressure rollers used as the pressure means. This is because if the respective surfaces of the pressure rollers are uneven, the coloring density of a color developed on a developer sheet. It has been known, however, that dirt mainly containing a binder for fixing photosensitive microcapsules on a microcapsule sheet and the contents of microcapsules adheres on the surface of pressure rollers of the pressure developing apparatus of the kind described above.
The reason why such dirt containing a binder and so on adheres on the surface of a pressure rollers will described by using FIG. 4. A microcapsule sheet 2 and a developer sheet 3 are put on each other and are being pressed across the width of the sheets between a pair of pressure rollers 1. By the pressing force, a binder 4 and so on are pushed out from the edge of the microcapsule sheet at a portion of the sheet sandwiched between the pressure rollers 1, so that the pushed out binder and so on adhere onto the surface of the pressure roller and the developer sheet. The wider the width of the microcapsule sheet than the width of the developer sheet is, the more remarkable the adhesion of the pushed out binder and so onto the surface of the pressure roller becomes. How to perfectly carry out cleaning of the pressure roller is one of the most important point for the pressure developing apparatus of the kind described above in order to keep good quality of a picture formed by the pressure recording apparatus.
It is therefore an object of the present invention to solve the above problem in the prior art pressure recording apparatus.
It is another object of the present invention to provide a pressure recording apparatus in which no dirt is generated on a pressure means.
In order to attain the above objects, according to the present invention, the pressure developing apparatus for pressing a microcapsule sheet carrying photo-sensitive microcapsules applied thereon and having a latent image formed thereon, together with a developer sheet carrying a developer applied thereon, comprises a pair of pressure members for pressing the microcapsule and developer sheets therebetween, at least one of the pair of pressure members having a pressing width for pressing the microcapsule sheet together with the developer sheet, the pressing width being selected to be narrower than that of each of the microcapsule sheet and the developer sheet.
Since the pressing width of the pressure member is made narrower than that of each of the microcapsule sheet and the developer sheet, the edge portions of the microcapsule and developer sheets are not pressed so that a binder and the contents of microcapsules disposed at the edge portion of the microcapsule sheet is not pushed out from the edge portion of the sheet.